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Time blindness in ADHD: why time feels different – and how planning still works

2026-09-28 · 4 min read

What research shows

A meta-analysis of 55 studies found broad differences in time perception in ADHD: short durations are discriminated less well, longer spans are estimated less accurately, and estimates vary more (Marx et al. 2022). A second meta-analysis across the lifespan found a medium effect (g = 0.69; Metcalfe et al. 2024).

To be honest: studies with adults only are scarce and mixed (Mette 2023). The direction is clear; the exact size in everyday work is not.

Why plans still fall apart

Almost everyone underestimates how long their own tasks take, because they focus on the plan and ignore past experience – the planning fallacy (Buehler et al. 1994, general population).

Add more variability and one task that takes twice as long is enough to wreck a minute-by-minute plan. It feels like personal failure, but it's mostly a maths problem.

Three habits that help

• Past duration over gut feeling: after a task, jot down how long it really took and estimate from that next time.
• Buffer by uncertainty: the less certain the estimate, the more room. A rough start is 50% extra – a rule of thumb, not a research figure.
• Make time visible: a visible countdown makes time tangible. Whether it measurably helps adults with ADHD hasn't been studied – try whether it supports or stresses you.

How Klarnext handles it

At the end of a block, Klarnext briefly asks whether it worked and records planned and actual minutes. From this, the app aims to learn which tasks you regularly underestimate. Time left is information only: you can pause it, extend it or hide the number – nothing expires or turns red.

This article provides general information and does not replace medical, psychological or therapeutic advice.